Parts for use in automotive engine rooms are required to have sufficient physical properties, e.g., sufficient strength, water resistance, heat resistance and resistance to calcium chloride (which is used as a snow melting agent), under higher temperature and higher humidity conditions. Conventionally, these parts are generally made of metal. In recent years, it has been contemplated to use automotive parts made of a fiber-reinforced resin (FRP) instead of the metal automotive parts to meet a need for weight reduction. Particularly, a glass fiber reinforcement thermoplastic resin containing glass fibers dispersed therein is excellent in versatility, processability, moldability and the like and advantageous in terms of costs and, therefore, is expected to find applications in the aforementioned field. A glass-fiber-reinforced thermoplastic resin molding product is typically produced by met-kneading a thermoplastic resin together with glass fibers, pelletizing the resulting mixture, melting the resulting pellets again and injection-molding the resulting melt (see, for example, PTL 1 to PTL 3).